In recent years, cryogenic technologies have been ever increasingly developed. The applications for cryogenic coolers are innumerable.
Cryogenic coolers, or cryocoolers, as they have come to be identified, are broadly categorized into one of two groups. These groups are based upon the method of gas flow regulation. The first group is referred to as Stirling coolers, and the second group is known as Ericcson coolers. In the former classification, gas flow is regulated by volume changes. In the second category, gas flow is regulated by valves.
Ericcson coolers are, in turn, sub-categorized as Solvey coolers, Gifford-McMahon coolers, and Postle coolers. The last type of cooler enumerated above is provided with a free displacer and includes self-activated valves.
The Postle cooler was, in turn, modified by being provided with a driven displacer. Additionally, modifications were made to provide both low and high pressure reservoirs or surge volumes. This modified Postle cooler is now known as the Gifford-McMahon cooler (or G-M cooler).
The Solvey cooler is, in many respects, similar to the G-M cooler. The most significant difference between these latter two coolers is that the Solvey cooler extracts work from an expanding gas by using a piston rather than a displacer.
Both the Solvey and the G-M coolers have both high and low pressure reservoirs. In these two types of coolers, the pressure within the low pressure reservoirs is kept below that present at any time prior to hot blow regeneration. As a result, fluid is permitted to exit the cooler by being drawn out of the cooler into the low pressure reservoir. Consequently, a heat exchange regenerator is cooled during the process in order to prepare for a subsequent cycle. Fluid within the low pressure reservoir is then compressed by an external compressor and then delivered to the high pressure reservoir.
All of such coolers known in the art have inherent problems. Illustrative is the fact that multiple reservoirs are provided. Additionally, external compressors are required. In essence, efficiency of such coolers is reduced in view of various factors.
It is to the problems and dictates of the prior art that the present invention is directed. It is an improved cryogenic cooler which addresses the problems of the prior art and provides unique solutions.